Combustion grate structure

ABSTRACT

For ease of casting and replacement of combustion grates, particularly for use in incinerator structures, the combustion grate plates and support blocks are made as single integral structural units, for example signal castings, the units being placed on grate beams which may be both stationary, or selectively, movable, and retained on the beams by their own weight and by matching inter-engaging shaped seats, for example grooves or rectangular beams with retaining rails against which the beams fit.

United States Patent 1191 Spillman etal.

14 1 Mar. 18, 1975 COMBUSTION GRATE STRUCTURE [75] Inventors: Kurt Spillman, Stafa; Georg Von Arx, Kloten, both of Switzerland Assignee: Von Roll'AG, Gerlafingen,

Switzerland Filed: Dec. 14, 1972 Appl. No.: 314,915

[30] Foreign Application Priority Data Dec. 22, 1971 Switzerland l873l/7l Int. Cl. F23g 3/00 Field of Search 110/8 R,.l8, 37, 38; 34/164; 432/122, 123

References Cited UNITED STATES PATENTS 3 Zl2,465 l0/l965 Cates, Jr. et al 1 [0/38 user. 110/8 R, 110/38 3,651,770 3/l972 Hotti 110/38 Primary Examiner-Kenneth W. Sprague Assistant E.raminerJames C. Yeung Attorney, Agent, or Firm--Flynn & Frishauf matching inter-engaging shaped seats, for example grooves or rectangular beams with retaining rails against which the beams fit.

9 Claims, 7 Drawing Figures 6 5 70 K... isle.--

PATENTED 3871.28 7

SHEET 1 0F 3 I LBS l COMBUSTION GRATE STRUCTURE CROSS REFERENCE OF RELATED PATENT U.S. Pat. No. 3,651,770, Mar. 28, 1972.

The present invention relates to a combustion grate structure, and more particularly to a combustion grate structure for use in incinerators particularly in refuse or trash incinerators, in which the substance to be burned is fed lengthwise of the combustion grate, and in which, alternately, adjacently arranged rows of fixed and movable combustion grate blocks and plates are provided.

Incinerator structures, and particularly incinerator structures to burn household refuse, municipal refuse, trash, and the like, are subjected to high temperatures, so that the combustion grate elements have to be replaced from time to time. It has been customary to provide. longitudinal beams (with respect to the feed direction of the substance to be burned, hereinafter for short called trash), to which grate blocks are secured, the blocks in turn supporting the grate elements or plates which extend transversely of the support beams. It has been proposed to secure the various blocks on which the grate elements or plates are secured, by means of screws, or bolts and the like, of the beams on which the blocks are supported. This type of attachment has a severe disadvantage, since the blocks can be removed from the beams only with great difficulty after they have been in use for some time, thus greatly interfering with replacement of the grate blocks, and the grate structures or plates on which the trash to be burned is physically located. The attachment screws, during operation of the incinerating structure, have the tendency to bake into the nuts, or matching thread elements so that it is frequently necessary to cut the blocks from the beams by means of cutting torches or the like. This is not only an expensive and time consuming operation but additionally destroys the very elements which are used to secure the blocks to the beams, and thus greatly increases the cost of replacement of parts of the grate structure.

Other types of grate structures have been proposed in which cast grate plates are utilized, cast in such a manner that they have ribs which project downwardly to fit into projecting hooks secured to the grate blocks, so that the plates can be hooked into the grate blocks below, thus avoiding the necessity of removal of the grate blocks themselves. This type of structure results in very heavy grate plates, and blocks, each of which must be cast separately and have a comparatively complicated shape, which increases the costs of the castings, and detracts-from their use. Machining for accurate fit of the plates, after casting, is usually economically not desired.

It is an object of the present invention to provide a grate structure, particularly for incinerator-type furnaces, in which the plates, or grate elements on which the trash (as defined) rests can be readily exchanged for new structures and which do not require complicated casting forms, nor have the tendency to bind with their attachment elements to the beams supporting the grate structure beneath. Subject matter of the present invention Briefly, the fixed, as well as the movable grate blocks and plates are placed on the beams beneath (some fixed, some movable) to be retained on the beams by their own weight, that is, by gravity, and held in place and position on the beams by means of matching interengaging, interlocking seats; the grate plates and the grate blocks, which physically reston the beams, are made as unitary integral structures, preferably as a single structural casting.

The invention will be described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 is a longitudinal sectional view of a fixed grate beam, according to the prior art, with grate blocks securedby screws;

FIG. 2 is a longitudinal, schematic sectional view through a known grate structure with a movable grate beam and movable grate blocks, the grate blocks being secured by screws;

FIG. 3 is a longitudinal schematic view, partly in section, of a grate system of the type of FIG. I, and utilizing the system of the present invention, the supporting beam being fixed;

FIG. 4 is a view similar to FIG. 3, for a movable support beam;

. FIG. 5 is a sectional view along lines V-V of FIG.

FIG. 6 is a detail view of a grate support structure in accordance with the prior art, to support a grate plate on a beam of FIGS. 1 and 2; and

FIG. 7 is a greatly enlarged partly sectional side view of a grate structure and its engagement with a grate beam therebeneath, in accordance with the present invention.

A combustion grate R,,, as known, is illustrated in FIG. 1. Fixed grate blocks 1 form support blocks for the grate plates 1 (FIG. 7), the support blocks 1,; being secured by attachment screws BS and nuts M to a fixed support or grate beam 2 The trash is fed downwardly in the direction of the arrow V.

The fixed grates, supported on fixed beams 2 alternate with movable beams and movable grates, in order to feed the trash. FIG. 2 illustrates a corresponding attachment arrangement to a beam 2, of the known grate R,,. The movable beam 2 has grate blocks 1 secured thereto by means of screws; the beam 2 is reciprocated by means of a fluid cylinder system AZ, and a piston rod ST secured by a hinge joint G to the beam, to reciprocate the beam in the feed direction V on the grate structure R The movable beam 2,, and with it the grate blocks I move in a linear path which is up wardly inclined. The grate beams themselves are supported on a pair of slide surfaces A which are upwardly inclined in direction of the feed V of the trash.

The structure in accordance with the present invention is illustrated in FIGS. 3 and 4. FIG. 3 shows an incinerator or furnace grate R in which unitary structures 1, including both blocks and transverse plates are placed on fixed beams 2, to be retained thereon merely by their weight and by the engagement or interlocking seat of the blocks and the beam. The blocks 1, and the transverse plates 1a are a single integral structural unit, that is, a single integral casting, as best seen to an enlarged scale in FIG. 7, which also shows the interengaging positioning of the seats on the beam 2 and the blocks 1.

The grate blocks and plates 1' of the grate structure, with respect to movable grate blocks, is'seen in FIG. 4. The drive for the movable beam 2 can be exactly that previously described in connection with FIG. 2 and is similar to the drive of known structures. FIG. 5 clearly shows how adjacent fixed and movable grate beams 2,

2', respectively, of the grate structure R of the present invention are arranged, together with the grate blocks 1, 1', respectively. Fixed grate beams and movable grate beams, with their grate blocks and plates are alternately arranged in adjacent rows located transverse to the feed direction V.

The fixed grate blocks 1, as well as the movable grate blocks 1 are formed with parallel upwardly extending wings, forming extensions of the side plates SW These side plates, or wings SW, form, together with the plates 6, 7 (FIG. 7) a channel structure, to guide the trash into channels and prevent small particles which may be included in the trash, such as screws, nails, spark plugs, or other similar elements from falling between the plates and interfering with movement of adjacent movable and stationary blocks, or causing wear at the sides. The upwardly drawn wings SW thus decrease the tendency of lateral wear of the blocks.

Grate blocks 1,, (fixed) or 1 (movable) of a customary known grate structure R are illustrated in greater enlargement in FIG. 6. As can be clearly seen,

the blocks l (fixed) or 1 (movable), respectively,

are secured by means of screws BS and nuts M to the beam underneath which may be fixed (2 or movable (2 respectively FIG. 6 further illustrates that the grate plate 1a,, is a separate element which has a pair of downwardly extending ribs R and R shaped to receive projections N, and N respectively, formed on the grate blocks 1 1,, respectively, and engaged from beneath by the projection to provide for an interlocking connection between the block 1 1,,,,, respectively, and the loosely attached plate l It has been found, during use, that the blocks, as well as the plates deteriorate during use, and require replacement. As can be readily seen, screws BS and nuts M will bake together and bind and, after use, can be removed from the underlying beam (which usually is not subject to temperature deterioration) only with great difficulty, if at all. Thus, replacement of the grate blocks themselves is very difficult, and can be carried out usually only by destruction of the screws BS and the nuts M, by cutting away the screws and nuts by means of cutting torches. The requirements of manufacture additionally, as can be seen from FIG. 6, require three separate casting molds, one for each of the two differentgrate blocks and one for the grate plate. The shape of the blocks, and the shape beneath the plates with the ribs and the interengaging, interlocking structure is difficult to cast.

FIG. 7 illustrates the structure in accordance with the present invention; the grate blocks 1 (fixed) and l (movable), respectively, ofthe grate R, (see also FIGS. 3 and 4) are connected to the underlying beams 2 (fixed) and 2' (movable), respectively, without the use of any attachement screws, or screw connections. Yet, they are readily removable, while still being securely held on the beam. The grate plate block combination 1, 1', respectively, seats on the associated beam 2, 2, respectively, by being loosely laid thereon, retained by its own weight and by an interlocking seat. The blocks 1, l and plates 1a, l'a, respectively, are single integral structural units and cast as such, in one single element. Both the fixed as well as the movable plates, with the attached blocks are identical in shape and size, so that only a single casting mold, or a single pattern is necessary for any one of the grate plate-block combinations of the entire grate structure. FIGS. 6 and 7 are reversed with respect to FIGS. 1 and 2, the feed of the trash again being indicated by arrow V. each one of the blocks 1, 1, respectively, is formed with transversely extending ribs 3. The beams 2, 2, respectively, are formed with transversely extending abutment rails 4, which may be angle structures to receive the ribs 3 and form a seat therefor. Preferably, the ribs 3 are rectangular, for example of square cross section; the rails 4 are shaped as angles located in advance of the ribs 3 (with respect to the feed direction V) forming a forward stop with respect to longitudinal movement of the 'ribs, and overlapping the ribs 3.

Each one of the plates la, l'a, respectively, is formed with a step 5 extending transversely to the feed direction V, so that the plates are sub-divided into a pair of plate sections 6, 7. The step 5 is formed with an opening 8 for combustion air to be supplied from beneath the grate structure R It is practically impossible that any components of the trash to be burned, and still in solid form, can plug the opening 8, or fall through opening 8 due to the inclined position of the grate R,., as best seen in FIGS. 3 and 4.

The upper surfaces 6 and 7,, of the plates, subdivided by step 5 and separated by air openings or nozzles 8 are inclined upwardly (with respect to the direction of feed of the trash V) and with respect to the downward inclination of the beams 2, 2', respectively, of the inclined grate structure R, (see FIGS. 3 and 4). The beams 2, 2' thus diverge with the upper surfaces 6,, and 7 of the grate plates 1,1, respectively, in the direction of the feed V of the trash, that is, towards the receiving end (at the right of FIGS. 3 and 4) of the great structure R FIG. 7 also shows the arrangement of the side wings SW, referred to in connection with FIG. 5, and previously described in detail.

The grate structure of the present invention has the substantial advantage that the blocks can be exchanged at any time, even after long time in use in the furnace, quickly, easily, and troublefree, and without destruction of any connection elements. An additional and substantial advantage resides in the fact that only one single casting mold must be prepared for both the blocks and the plates, which substantially decreases the overall costs of the grate structure, as well as of replacement parts. The single, unitary casting of the blocks and the plates decreases the weight of the blocks and plates, taken together, with respect to the individually cast items by a substantial amount, since interlocking areas of heavy cast metal are no longer required. The particular structure also permits application of combustion air to the trash, to be placed on the upper surfaces 6,, and 7,, in spite of the fact that the grate plates can be made to have a substantial lateral extent. The structure is so arranged that, in spite of the opening for application of combustion air, trash is effectively prevented from falling through the combustion air apertures.

To provide free circulation of combustion air into the bed, grate cutters or grate pokers 10 are swingably secured to the fixed grate bar or beam 2 They swing back and forth, operated by a link 11, linked eccentrically to the grate cutter and driven from a shaft 12 by means of an eccenter connection, the shaft 12 itself being operated by a suitable motor, for example a pneumatic cylinder (not shown). The showing of the grate cutter has been omitted from FIGS. 3-7 for simplicity. The grate cutter is a flat swinging raking element which is pivoted within a window-like recess of a stationary grate block secured to the fixed grate bar 2 and is used to rake up, or to poke the layer or bed of fuel lying on the combustion grate R The movable grate bars 2,, which alternate with the fixed grate bars 2 do not have grate cutters affixed thereto.

It is a primary advantage of the inventive block 1, 1 (FIG. 7) integral withthe plates la, l'a, respectively, that the single units can be made much lighter than the separate ones. Thus, single castings are approximately 40 percent lighter than the sum, of the weights of the prior art blocks l or I together with the separate grate plate l .as shown in FIG. 6. The construction has the additional advantage that replacement of the new blocks 1, 1' (FIG. 7) is much faster, and can be accomplished with more ease and less insertion trouble than interchange of the blocksaccording to FIG. 6. Removal of separate holding screws, such as screws BS and nuts M (FIG. 6) is not necessary; yet, these screws have to be removed in order to free the blocks from the seating noses N N since these noses are also subject to wear or destruction due to mechanical abrasive effects resulting from slag, nails, screws, and other debris falling between the slots of neighboring fixed and movable grate beams 2 2 The structure of the present invention, see particularly FIG. 7, permits ready interchange without removal of any screw elementswhich have a tendency to freeze or burn-in. The grate blocks to be used both for the fixed as well as for the movable beams can be made to be identical, with the same shape and size, reducing not only the costs in casting but also reducing requirements for storing replacement elements and parts of the furnace structure. The grate structures themselves have to be replaced from time to time.

Various changes and modifications may be made within the inventive concept; for example, the air opening or aperture 8 may be an elongated slot, a single opening, or a plurality of openings formed in the step between the individual plate sections 6, 7; different types of attachment ribs 3 and holding rails 4 may be used, the structure being shown providing an effective, easily made engaging seat.

The plates, and plate sections and plate blocks can be placed on the beams in various arrangements, and in a preferred form are so placed that the leading plate'section 6 (FIG. 7), with respect to the feed direction of the trash, overlaps the trailing end of the trailing plate of an adjacent block and plate unit, to prevent trash particles from falling between adjacent plate units (see also FIGS. 3 and 4). To provide for proper balance of the units, the units are supported at two engaging seats and abutment rails 4, one of the seats formed by rib 3 and abutment rail 4 being preferably located in the region of the step 5, or in advance thereof and to provide for reliable seating of the block plate units on the respective beam.

We claim:

1. In a combustion grate structure having spaced grate plates (6, 7) on which the substance to be burned is adapted to be positioned, grate beams (2, 2) located beneath the grate plates, grate support blocks located selected grate beams (2 FIG. 4) being movable along thedirection of feed of said substance and other grate beams (2 FIG. 3) being stationary on said support means, said movable (2') and stationary (2) beams being located adjacent each other, the improvement wherein the grate plates (la, 1 a; 6, 7) and the support blocks on the movable as well as on the stationary beams are identical, single, integral castings (l, 1') so that the plates and the blocks form plate portions la, 1'0) and block portions of said castings, said castings being placed on the respective movable and stationary grate beams (2, 2') to be retained thereon by gravity, the upper surface of the movable as well as the stationary beams and the lower surface of the block'portions of said castings being formed with interlocking, shaped matching seats, said matching seats comprising ribs (3) formed on each of the block sections (1a, 1'a) and extending transversely to the grate beam, and abutment rails (4) formed on the grate beams (2, 2) extending transversely to the grate beams thereby permitting random placement of any plate-block casting on any seat on any beam, and retention of said plateblock castings on the beam, by gravity and by the interlocking seat.

2. Structure according to claim 1, wherein the ribs (3) have a generally rectangular cross section;

and the abutment rails (4) are generally angle-shaped and located in advance of, and overlapping the ribs, with respect to the feed direction (V) of said substance to form said interlocking seats.

3. Structure according to claim I, wherein each grate plate section (In, l'a) is formed with two plate subdivisions (6, 7) which are located longitudinally adjacent each other, with respect to the feed direction (V) of the substance, and have vertically stepped adjacent edges to form a step (5) extending transversely of the grate beam (2, 2');

and at least one combustion air opening (8) formed in the step (5) between the plate sub-divisions.

4. Structure according to claim 1, wherein the combustion grate (R is inclined downwardly and said substance is applied to the grate at its highest elevation and wherein the upper support surfaces (6,, 7,) of the plate sections (1a, l'a) are upwardly inclined with respect to the inclination of the grate in the direction of feed (V) of said substance.

5. Structure according to claim 1, comprising upwardly extending side walls (SW extending from the sides of the integral casting to prevent escape of particles from said substance between the integral castings on said grate beams.

6. Structure according to claim 1, wherein the lower surfaces of the block sections are formed with two seats spaced longitudinally, and said beams are formed with matching seats arranged longitudinally of the beam.

7. Structure according to claim 3, wherein the lower surfacesof the block sections are formed with two seats spaced longitudinally, one of said seats being arranged in the region beneath said step (5).

8. Structure according to claim 7, wherein the leading plate sub-division, with respect to the feed direction of said substance, extends above and overlaps the trailing plate sub-division of an adjacent integral casting, when placed on the respective beam.

,9. In a combination grate structure having spaced grate plates (6, 7) on which the substance to be burned is adapted to be positioned, grate beams (2, 2') located beneath the grate plates, grate support blocks located between the grate beams and the grate plates (6, 7) to removably support the grate plates on the beams and space the plates from the beams;

means supporting said grate beams;

selected grate beams (2' FIG. 4) being movable along the direction of feed of said substance and other grate beams (2 FlG. 3) being stationary on said support means, said movable (2') and station ary (2) beams being located adjacent each other, the improvement wherein the grate plates (la, l'a; 6, 7) and the support blocks on the movable as well as on the stationary beams are identical, single, integral castings (l, 1') so that the plates and the blocks formplate portions (la, l'a) and block portions of said castings, said castings being placed on the respective movable and stationary grate beams (2, 2') to be retained thereon by gravity, upwardly extending side walls (SW extend from the sides of the integral casting to prevent escape of particles from said substance between the integral castings on said grate beams, the upper surface of the movable as well as the stationary beams and the lower surface of the block portions of said castings being formed with interlocking, shaped matching seats, to permit random placement of any plate-block casting on any beam, and retention of said plate-block castings on the beam, by gravity and by the interlocking seat. 

1. In a combustion grate structure having spaced grate plates (6, 7) on which the substance to be burned is adapted to be positioned, grate beams (2, 2'') located beneath the grate plates, grate support blocks located between the grate beams and the grate plates (6, 7) to removably support the grate plates on the beams and space the plates from the beams; means supporting said grate beams; selected grate beams (2'' - FIG. 4) being movable along the direction of feed of said substance and other grate beams (2 -FIG. 3) being stationary on said support means, said movable (2'') and stationary (2) beams being located adjacent each other, the improvement wherein the grate plates (1a, 1''a; 6, 7) and the support blocks on the movable as well as on the stationary beams are identical, single, integral castings (1, 1'') so that the plates and the blocks form plate portions (1a, 1''a) and block portions of said castings, said castings being placed on the respective movable and stationary grate beams (2, 2'') to be retained thereon by gravity, the upper surface of the movable as well as the stationary beams and the lower surface of the block portions of said castings being formed with interlocking, shaped matching seats, said matching seats comprising ribs (3) formed on each of the block sections (1a, 1''a) and extending transversely to the grate beam, and abutment rails (4) formed on the grate beams (2, 2'') extendIng transversely to the grate beams thereby permitting random placement of any plate-block casting on any seat on any beam, and retention of said plate-block castings on the beam, by gravity and by the interlocking seat.
 2. Structure according to claim 1, wherein the ribs (3) have a generally rectangular cross section; and the abutment rails (4) are generally angle-shaped and located in advance of, and overlapping the ribs, with respect to the feed direction (V) of said substance to form said interlocking seats.
 3. Structure according to claim 1, wherein each grate plate section (1a, 1''a) is formed with two plate sub-divisions (6, 7) which are located longitudinally adjacent each other, with respect to the feed direction (V) of the substance, and have vertically stepped adjacent edges to form a step (5) extending transversely of the grate beam (2, 2''); and at least one combustion air opening (8) formed in the step (5) between the plate sub-divisions.
 4. Structure according to claim 1, wherein the combustion grate (Re) is inclined downwardly and said substance is applied to the grate at its highest elevation and wherein the upper support surfaces (6o, 7o) of the plate sections (1a, 1''a) are upwardly inclined with respect to the inclination of the grate in the direction of feed (V) of said substance.
 5. Structure according to claim 1, comprising upwardly extending side walls (SW1) extending from the sides of the integral casting to prevent escape of particles from said substance between the integral castings on said grate beams.
 6. Structure according to claim 1, wherein the lower surfaces of the block sections are formed with two seats spaced longitudinally, and said beams are formed with matching seats arranged longitudinally of the beam.
 7. Structure according to claim 3, wherein the lower surfaces of the block sections are formed with two seats spaced longitudinally, one of said seats being arranged in the region beneath said step (5).
 8. Structure according to claim 7, wherein the leading plate sub-division, with respect to the feed direction of said substance, extends above and overlaps the trailing plate sub-division of an adjacent integral casting, when placed on the respective beam.
 9. In a combination grate structure having spaced grate plates (6, 7) on which the substance to be burned is adapted to be positioned, grate beams (2, 2'') located beneath the grate plates, grate support blocks located between the grate beams and the grate plates (6, 7) to removably support the grate plates on the beams and space the plates from the beams; means supporting said grate beams; selected grate beams (2'' - FIG. 4) being movable along the direction of feed of said substance and other grate beams (2 -FIG. 3) being stationary on said support means, said movable (2'') and stationary (2) beams being located adjacent each other, the improvement wherein the grate plates (1a, 1''a; 6, 7) and the support blocks on the movable as well as on the stationary beams are identical, single, integral castings (1, 1'') so that the plates and the blocks form plate portions (1a, 1''a) and block portions of said castings, said castings being placed on the respective movable and stationary grate beams (2, 2'') to be retained thereon by gravity, upwardly extending side walls (SW1) extend from the sides of the integral casting to prevent escape of particles from said substance between the integral castings on said grate beams, the upper surface of the movable as well as the stationary beams and the lower surface of the block portions of said castings being formed with interlocking, shaped matching seats, to permit random placement of any plate-block casting on any beam, and retention of said plate-block castings on the beam, by gravity and by the interlocking seat. 